Fractionation of mineral oil



Feb. 18 1935. Q SWIFT 2,031,234

FRAGTIONATIYON OF MINERAL OIL Filed May 9, 1932 115 Z r 1? l 1/2 {g3 908 1 10/ F 104 ms l {05/ 3 107 l 5 J 02 h 847 F92;

. as /68 as as a as 55 m l 64 62 65 66 67 INVEN'fOR.

Claude E6209? 3W I a Z a ATTORNEY.

, 15 -ment as may be required for the production of the viscosity of the final product this may be Patented Feb. 18, 1936 I UNlTED STATES PATENT; OFFlCE 7 2,031,284 FRACTIONATION OF MINERAL OIL Claude E. Swift, Glendale, Calif assignor to Union Oil Company of California, Los Angeles, Calii., a corporation of California Application May 9, 1932, Serial No. 010,101

9 Claims. (Cl. 196-13) This invention relates to a process for the the inventor has caused the separation of the production of lubricating oil. More specifically, ,oil from the asphalt by the use of certain selective it relates to a process for the production of lubrisolvents which have a high solvent power for oil eating oil from oil containing asphalt or apshalt but a poor solvent power for asphalt. Thus the and wax. crude oil is first subjected to distillation for the At the present time it is customary to produce separation of the light hydrocarbons present and lubricating oil from asphaltic crude oil by disthen the residue is extracted with such solvents tillation. The crude oil is first subjected to fracas liquid propane or other light liquid hydrotional distillation for the removal of the light carbons for the separation of the asphalt from 10 fractions present, such as gasoline, kerosene and the oil. The solvent solution of oil is then disgas oil, after which the lubricating oil fractions tilled to separate the solvent from the oil after remaining in the still residue are distilled away which the oil may be treated by methods confrorn the asphaltic still residue. These lubriventional in the art for the production of a catmg oil distillates are then given such treathighly refined product. When it is desired to vary w finished lubricating oil. done in either of two manners. First, by varying Providing the crude oil contains wax this matethe extent of the distillation of the crude oil rial is partially separated from the still residue prior'to extraction and second, by blending-the v t by the distillation along with the lubricating oil extracted heavy residual oil with varying c1uan-- 20 fractions. The presence of wax in the lubricating titles of the fighter distilled overhead fractions. oil fractions causes the finished lubricant to have The first method is quite inflexible and the variaa high pour point or high congealing temperature tions in viscosity of the final products are quite which is undesirable. It, therefore, becomes neclimited. The second method is open to objection essary to separate a substantial portion of the because the light overhead distillates used for 25 wax-from these distillates in order to produce a blending -usually are highly susceptible to a lubricating oil having the desired low pour point change in viscosity with a change in temperature characteristics. 7 Any of the methods conventional and when mixed with the extracted heavy rein the art, such as cold settling, coldpressing sidual oils have this same undesirable effect upon 0 or centrifuging may be employed to separate the temperature viscosity susceptibility of the the wax from the oil. blended product.

It h e p i t d u i a pat nt icat on. A more flexible method of separating the lubriflled by U- 3.2 m s1N0. 8 dated u cating oil constituents of asphaltic oil into frac- 7, 1930, that dlsillleflen metlmds be tions of varying viscosity consists in treating such Ployed separating heavy lubricating oil with suitable solvents which are capable of fractions r asphalt: drudees without an successively extracting oil fractions of increasing pai-rment of certainvaluable characteristics 'pos-' .viscosities. Thus when a residual asphaltic oil, :fassed by these fr-actmns m the original undis" produced by distilling oil the light fractions from illed crude 011. Distillation of the lubricating oil asphamc crude on is 4 sue ce S81v8] y extracted with constituentsof crude oil, and especially crude oil containing asphalt, appears to render the alcohol, alcohol and ether, or alcohol and benzol, 40 overhead fractions or distillates more susceptible there Produced a series of on fractions with to a change in viscosity with a change in temmending, Mtiefi- The undesirable feature perature. Just what happens during the distillain this procesahowever, re in the u ili y 5 tion of these fractions to produce the above is of certain of the asp e bodies in the solvent 4 not known, however, it is thought that the high s luti n or 011. Thus the oil fr i ns which ar 5 temperatures necessary for vaporizing the oil produced by successively extracting an asphaltic causes some. change in the molecular configuraoil with such solvents are characterize by an imtion of the oil which renders it more susceptible desirable dark color due to the presence of asphalt to a change in viscosity with a change in temperain the 011. This undesirable constituent in the ture. Furthermore, this increase in the temperalubricating Oil frac i n m be removed before ture 'viscosity susceptibility of the oil appears finished lubricant canbe produced. The removal I to be more pronounced where the distillation is 01 the aspha t 8 be a e y the e O a d carried out in the presence of asphalt. In order 3 Or other chemicals capable of coagulatin the to conserve these valuable inherent charactera phfl lc bodies P t by a Combination of istics possessed by the lubricating oil fractions acid treatment and bleaching with .clay but such 5 eliminates the undesirable features described in i the foregoing process. My process consists in commingling asphaltic oil with a solvent in which the asphalt is substantially insoluble and the oil substantially completely soluble, separating the solvent solution of oil from the undissolved asphalt, removing the solvent from the substantially asphalt-free oil and then separating the extracted oil by the use of appropriate solvents into fractions of varying viscosity.

The asphaltic oil which .I extract is obtained from those crude oils which contain asphalt. The crude oil containing asphalt is first distilled under carefully controlled conditions with fire and steam for the separation of gasoline, kerosene and gas oil present. Care is exercised in removing these light constituents from the crude oil as quickly as possible and without employing excessive temperatures which would be injurious to the valuable lubricating oil constituents present. The residue so produced is then cooled and extracted with a solvent capable of dissolving the oil but in which asphalt is substantially insoluble.

For the separation of the asphalt from the oil I find the light hydrocarbons which are vaporous at ordinary temperature and pressure very satisindustry. They are the overhead thus obtained.

They are liquefied by compression and cooling in the conventional manner and drawn oif into pressure chamber where they are maintainedin the liquid state until they are used. A typical analysis of such a fraction is 6.72% ethane, 72.20% propane, 19.91% isobutane and 1.17% normal butane and the necessary pressure to maintain this fraction in a liquid state is approximately 125 pounds per square inch gauge at 70 F. I

After the separation of the asphalt from the solvent solution of oil the latter iSdistilled to remove the solvent and recover the substantially asphalt-free oil. The oil is then subjected to successive extraction with alcohol for the production of a series of oil fractions of varying viscosity. Methyl, ethyl, propyl, isopropyl, butyl and isobutyl alcohol or mixtures. of these alcohols may be employed to a good advantage in separating the substantially asphalt-free oil 'into fractions.

of varying viscosities. I find in general, however, that the alcohols of the higher molecular weights are more suitable for carrying outv my process than the alcohols of the lower'molecular weights.

I may also employ solutions of these alcohols in Furthermore, I find that it is only practical to employ ether or benzol to a good advantage.

alcohols which are substantially free from water as the presence of this material in the alcohol;

to dehydrate the alcohol by any of the methods common to the art. Thus the alcohol may be commingled with calcium oxide or anhydrous copper sulphate and subsequently distilled for the production of a solvent alcohol sufficiently free from water to be employed in my process.

It is, therefore, an object of my invention to produce lubricating oils of varying viscosity from crude oils containing asphalt.

It is another object of my invention to separate the lubricating 011 components from asphaltic oil under conditions which will conserve the inherent temperature viscosity susceptibility characteristics of the oil and then separate the oil into fractions of varying viscosity.

It is another object of my invetnion to commingle asphaltic residual oil with liquid propane, separate the oil from the asphalt and then separate the asphalt-free oil into a plurality of fractions of varying viscosities with alcohol.

It is still another object of my invention to separate wax and asphalt bearing oils into asphalt, wax and a plurality of oil fractions under such conditions that the inherent viscosity temperature susceptibility characteristics of the oils are not impaired during the process of separation.

The accompanying drawing is a schematic arrangement of apparatus in which I may carry out my process.

In the drawing, crude oil in tank I is withdrawn through valve 2 andline 3 to pump 4 which forces it through line 5 into agitator 6 where it is mixed with a stream of liquid propane coming from tank I] through valve 12, line l3, pump I4 and line IS. The thoroughly mixed mass in agitator 6 is removed through line I to settling chamber 8 where the insoluble asphalt is allowed to settle out and is removed through valve 3 and line Ill.

The propane solution of oil is substantially free from asphalt and is removed from settling chamher 8 through valve I8 and line H to pump it which forces it through line 43, valve l0, line 44, valve 38 and line 39 to vaporizer 43 where by aid of steam introduced through closed coil ll the propane present in the oil is vaporized and passes by means of valve 46 and line 46 to compressor 41 which forces it through line' 26 to condenser 21 where it is liquefied and passes by means of line 28 to propane storage tank ll.

Where wax is present in the oil under treatment the following modification inthe process is employed:

After removal of the insoluble asphalt in settling chamber 8, the propane solution of wax and oil passes by means of valve l6, line l2 to pump is which forces itthrough line 43. valve 23 and line 2| to chiller 22 where suillcient liquid propane is allowed to vaporize at reduced pressure to obtain a temperature sufnciently low to cause thorough precipitation of the wax. The vaporized propane in chiller-22 is removed through valve 23 and line 24 to compressor 2! which forces it through line 26 to condenser 21 where it is liquefled and passes by means of line 23 to propane storage tank II. The chilled propane solution of oil carrying precipitated wax is removed from chiller 22 through valve 23 and line 33 to pump 3| which forces it through line 32 to "filter press or wax separating means 33 wherethe wax is separated from the propane solution of .oil and is removed through valve 3! and line 35. The propane solution of oil, substantially free of wax is removed from wax separation means 33 through line 36, valve 31 and line 33 to vaporizer Ill where the propane present is removed from the oil in the same manner as has previously been described.

The oil, substantially free from asphalt, in vaporizel 40 is removed through. valve 42 to pump hydrator I20 through 43 which forces it through line I I8 to agitator 55 where it is thoroughly mixed with hot alcohol coming from alcohol storage tank 49 through valve 50, line 5I, heat exchanger 52, line 53 and valve 54. In case insuillcient heat is supplied by the alcohol vapors in heat exchanger 52 to raise the liquid alcohol in line 53 to the proper temperature I may supplement other heating means not shown. The mixture of oil and hot alcohol passes to separating tower 58 where the oil dissolved in alcohol separates as the upper phase and the undissolved oil separates as the lower phase. The alcohol solution of oil constitutin the upper phase is removed through line 51 to centrifuge 58 where anyentrained undissolved oil globules are removed through line 58. The alcohol solution of oil from centrifuge 58 passes by means of line 60 to pump GI which forces it through line 83 to heater 82 where the temperature of the mass is raised sufflciently high to vaporize the alcohol. The heated mass passes from heater 82 through line 63 into separating tower 64 where the unvaporized oil separates from the alcohol vapor and is removed through valve 85 and line 68 to storage tank 61. The alcohol vapor in separator 84 is removed through line 68 through heat exchanger 52 where a portion of the heat in the alcohol vapor is utilized to raise the temperature of the liquid alcohol passing to the extraction process. The partially cooled alcohol vapor in heat exchanger 52 is removed through line 89 to condenser 10 where it is liquefied and passes by means of line H to pump 12 which forces it through line I3 to any suitable means of dehydration I20, such as has been previously described. The dehydrated alcohol passes from deline I2I into alcohol storage tank 49.

The insoluble oil phase in separator 58 is removed through valve I22 into line 14 where it is combined with the separated entrained oil in line 50. This oil passes to line I8 where it meets a stream of hot alcohol coming through line 53 and valve 15 and the mixed stream of oil and hot alcohol passes to agitator 11 where they are thoroughly mixed and then pass to separating tower 18, where the alcohol solution of soluble oil is allowed to separate as the upper phase and is removed through line 19 to centrifuge where the entrained insoluble oil globules present arated and passed out through line 8|. The hot alcoholic solution of oil passes from centrifuge 80 through line 82 to pump 84 which forces it through line 85 into heater 88 where the temperature of the mass is raised sufllciently high to vaporize the alcohol. The heated mass then pames through line 81 into separator 88 where the unvaporized oil is removed through valve 88 and line 90 to tank Ill. The separated alcohol vapor is removed through line 92 into line 68 where it is finally returned to alcohol storage tank 69 in the same manner as previously described.

The insoluble oil phase in separator 18 is removed through valve I23 into line 83 along with the separated entrained oil in line 8|. This oil passes through line 83 to'agitator 85 where it is mixed with hot alcohol coming through line 53 and valve 84. The thoroughly a tated mass passes from agitator 95 into separator 88 where the alcoholic solution of oil separates from the remaining undissolved oil as the upper phase. This phase is removed through line 81 to centrifuge 88 where any undissolved on present is separated and passes out through line 98. The alcoholic solution of oil in centrifuge are sepmoved through line I25 to pump I00 which forces it through line IN to heater I02 where the temperature is raised sufiiciently high to vaporize the alcohol. The heated mass then passes through line I03 to separator I04 where the unvaporized oil separates and is removed through valve I05 and line I06 into storage tank I01. The vaporized alcohol is removed from separator I04 through line I08 into line 88 where it is returned to alcohol storage tank 48 in the same manner as previously described. 5

The lower insoluble phase in separator 95 is removed through valve I24 through line I09 where it is combined with the insoluble oil from centrifuge 98 in line 89 and passes to pump I I0 which forces it through line III to heater II2 where the temperature is raised sufficiently high to vaporize any alcohol present. The heated mass then passes through line II3 to separator Ill where the unvaporized oil settles out and is removed through valve H5 and line II6 to storage tank II'I. The separated alcohol vapor is removed from separator II4 through line II8 into line 68 where it is returned to alcohol storage tank .49 in the same manner as previously described.

Furthermore, when the oil contains wax I may employ wax anti-solvents to aid its separation from the oil. For example I may .dissolve the waxy oil in a diluent such as liquid propane and then add alcohol, acetone, acetone and benzol, or methyl formate to aid in precipitating the wax. If necessary the waxy oil dissolved in liquid propane and containing a quantity of wax anti-solvent may be chilled to cause thorough precipitation of the wax. The chilling may be accomplished by vaporizing some of the1 liquid propane diluent under reduced pressure or by liquid ammonia or other refrigerating means.

As an example of the preferred method of carrying out my process, an asphaltic residual oil obtained by carefully distilling out the gasoline, kerosene and gas oil present in tank I is mixed with a light volatile liquid hydrocarbon such as liquid propane in the proportion of one part of residual oil to five parts of liquid propane. The insoluble asphalt is separated from the propane solution of oil through line I0 of chamber 8 and the propane solution of substantially asphaltfree oil is then passed to vaporizer 40 where the propane is separated from the oil.

The hot oil' in vaporizer 40 is removed through valve 2, pump 43 and line H8 from whence it passes to the foregoing described means for successive extraction with alcohol. The extraction is preferably carried out at a temperature near the boiling point of the alcohol. The predetermined temperature'of the oil entering the extraction apparatus may be obtained by the use of the steam coil in vaporizer 40. After the preheated oil enters the extraction apparatus no further heat is required to maintain the proper temperature other than that furnished by the preheated alcohol withdrawn from heat exchanger 52. The ratio of the oil and alcohol entering the extraction apparatus will depend largely upon the character of the fractions desired. Any one of the succesive fractions may be enlarged by maintainng oil in that particular extraction step. After separation of the oil into the desired number of fractions the particular grades obtained may be stored in tanks 81, 9|, I01 and H1 and where intermediate products are desired these fractions may be blended.

of my process and are not to be construedas limiting the invention. which I claim.

I claim:

1. A method for the fractionation of oil containing asphalt which comprises commingling said oil in a light hydrocarbon solvent, separating the light hydrocarbon solvent to separate asphalt solution of oil from the undissolved asphalt, separating the light hydrocarbon solvent from the substantially asphalt-free oil, successively extracting said substantially asphalt free oil with an alcohol to form a plurality of fractions and separating said fractions.

2. A process for the fractionation of oil containing wax which comprises dissolving said oil under superatmospheric pressure in a light volatile hydrocarbon, vaporizing a portion of said solvent to chill the oil and precipitate the wax, separating the precipitated wax from the solvent solution of oil, separating the solvent from the wax-free oil and successively extracting said wax free oil with alcohol to produce a plurality of fractions and separating said fractions.

3. A process for the fractionation of oil containing wax which comprises dissolving said 011 under superatmospheric pressure in liquid propane, releasing the pressure and lowering the temperature of the oil sufilciently to precipitate the wax, separating the precipitated wax from the propane solution of oil, separating the propane from the wax-free oil and separating said substantially wax free oil into a plurality of fractions by successive extraction with alcohol and separating said fractions.

4. A process for the fractionation of oil containing wax which comprises commfingling said oil under superatmospheric pressure with liquid propane containing a wax anti-solvent, releasing the pressure and vaporizing propane to chill the oil sufficiently to precipitate the wax, separating the precipitated wax from the oil dissolved in propane and wax anti-solvent, separating the oil from the propane and wax anti-solvent and separating the wax-free oil into a plurality of fractions by successive extraction with alcohol.

5. A process for the fractionation of oil containing asphalt and wax which comprises commingling said oil with a light hydrocarbon solvent capable of dissolving the oil and wax but not the asphalt, separating the solvent solution phalt from the of oil and wax from the undissolved asphalt, chilling the solvent solution of oil to a temperature sufiiciently low to precipitate the wax, separating the precipitated wax from the solvent solution of oil, removing the solvent from the oil and subsequently separating the oil into a plurality of fractions bysuccessive extraction with alcohol.

6. A process for the fractionation of oilcontaining asphalt and wax which comprises commingling said oil under superatmospheric pressure in liquid propane, separating the propane solution of oil and wax from the undissolved asphalt, releasing the pressure and vaporizing liquid propane to chill the oil and precipitate the wax, separating the precipitated wax from the propane solution of oil, separating the propane from the oil, extracting the oil with alcohol to form a plurality of fractions and subsequently separating the alcohol from said fractions.

7. A process for the fractionation of oil con taining asphalt which comprises commingling said oil with a normally gaseous hydrocarbon solvent to separate the asphalt, separating the asoil dissolved in said solvent, separating the solvent from the-oil, extracting said substantially asphalt free oil with alcohol to produce an oil phase dissolved in said alcohol and an oil phase insoluble in said alcohol and separating said phases.

8. A process for the separation of oil containing asphalt into fractions which comprises commingling said oil with liquid prr pane to separate the asphalt, separating the asphalt from the oil dissolved in liquid propane, separating the propane from the oil, extracting the substantially asphalt free oil with alcohol to form an oil phase dissolved in alcohol and an oil phase insoluble in said alcohol and separating said phases.

9. A process for the separation of oil containingasphalt into fractions which comprises commingling said oil with a liquefied normally gaseous hydrocarbon solvent to separate asphalt, sep-, 'arating the asphalt from the oil dissolved in said solvent, separating the solvent from the oil and extracting the substantially asphalt free oil into a plurality of fractions having successively higher viscosities with a solvent and separating said fractions.

CLAUDE E. SWIFT.

CERTIFICATE OF CORRECTION.

"Potent No. 2,031,234. February 18, 1936.

CLAUDE E. SWIFT.

I It is hereby certified that error appears in the printed specification of the abovexnumbered patent requiring correction as follows: Page 4, first "column, lines 8 end 9, claim 1, strike out the, words "to sep erate' asphalt? and insert the same aftex fl'solvent" and before the coma in line 7} same: 1 glei-m'; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the'case in the Patent "QM-ice. t

. Signed and sealed this 25rd day of .Febrparj, A. o. 1937. 

